The subject invention relates to a catheter and introducer needle assembly that includes a needle shield that will safely shield the sharp distal tip of the introducer needle after the needle has been used to insert the catheter into a patient.
Catheters, particularly intravenous (IV) catheters, are used for infusing fluid, such as normal saline solution, various medicaments and total parenteral nutrition, into a patient or withdrawing blood from a patient. Peripheral IV catheters tend to be relatively short, and typically are on the order of about two inches or less in length. The most common type of IV catheter is an over the needle peripheral IV catheter. As its name implies, an over the needle catheter is mounted over an introducer needle having a sharp distal tip. The catheter and the introducer needle are assembled so that the distal tip of the introducer needle extends beyond the distal tip of the catheter with the bevel of the needle facing up away from the patient""s skin.
The catheter and introducer needle assembly is inserted at a shallow angle through the patient""s skin into a peripheral blood vessel, i.e a smaller blood vessel that is not connected directly to the heart but is one of the branches of the central blood vessels that is directly connected to the heart. In one technique, the introducer needle and catheter are inserted completely into the blood vessel together. In another technique, the introducer needle is partially withdrawn into the catheter after the initial venipuncture. The catheter is then inserted completely into the blood vessel. In order to verify proper placement of the assembly in the blood vessel, the clinician confirms that there is flashback of blood in the needle and in a flashback chamber located at the proximal end of the needle and which is typically formed as part of the needle hub. Once proper placement is confirmed, the clinician applies pressure to the blood vessel by pressing down on the patient""s skin over the distal tip of the introducer needle and the catheter. This finger pressure occludes further blood flow through the introducer needle. The clinician withdraws the introducer needle, leaving the catheter in place, and attaches a fluid delivery device, a PRN or a deadender cap to the catheter hub. Once the introducer needle is withdrawn from the catheter, it is a xe2x80x9cblood contaminated sharpxe2x80x9d and must be properly handled.
In recent years, there has been great concern over the contamination of clinicians with a patient""s blood and a recognition that xe2x80x9cblood contaminated sharpsxe2x80x9d must be immediately disposed. This concern has arisen because of the advent of currently incurable and fatal diseases, such as Acquired Immunosuppressive Deficiency Syndrome (xe2x80x9cAIDSxe2x80x9d), which can be transmitted by the exchange of body fluids from an infected person to another person. Thus, contact with the body fluid of an AIDS infected person must be avoided. As noted above, if an introducer needle has been used to place a catheter in the vein of an AIDS infected person, the introducer needle is a vehicle for the transmission of the disease. Although clinicians are aware of the need to properly handle xe2x80x9cblood contaminated sharpsxe2x80x9d, unfortunately in certain medical environments, such as emergency situations or as a result of inattention or neglect, needlesticks with a contaminated introducer needle still occur.
As a result of the problem of accidental needlesticks by xe2x80x9cblood contaminated sharpsxe2x80x9d, various needle shields have been developed. Generally, such needle shields work for their intended purpose but could be improved. For example, some needle shields are bulky, difficult to use or require special features or techniques to be operative.
It is therefore an object of this invention to provide a needle shield that is compact.
It is another object of this invention to provide a needle shield that is simple and easy to use.
It is still another object of this invention to provide a needle shield that requires no special features or technique to be operative.
The catheter and introducer needle assembly with needle shield of this invention includes a catheter having a distal end and a proximal end connected to the distal end of a catheter hub. The introducer needle has a sharp distal tip and a proximal end connected to the distal end of a needle hub. A flashback chamber is defined in the needle hub. Typically a porous plug is located in the open proximal end of the flashback chamber to allow air to escape from the flashback chamber when blood enters the flashback chamber from the introducer needle. The catheter is coaxially disposed over the introducer needle so the sharp distal tip of the introducer needle is distal of the distal end of the catheter. The introducer needle also defines, along a distal portion thereof, an enlarged diameter portion with a distally facing shoulder immediately distal thereof and a tapered portion immediately proximal thereof. The enlarged diameter portion cooperates with a needle shield to prevent unwanted proximal movement of the introducer needle with respect to the needle shield once the introducer needle has been withdrawn into the needle shield after use. The distally facing shoulder cooperates with the needle shield to prevent unwanted distal movement of the introducer needle once the introducer needle has been withdrawn proximally into the needle shield after use.
The needle shield includes a main body portion defining a longitudinally extending passage through which the introducer needle extends. The needle shield also includes a means for engaging the distally facing shoulder of the introducer needle to prevent distal movement of the introducer needle once the introducer needle has been proximally withdrawn into the needle shield. The longitudinally extending passage has a proximal portion that has a diameter sufficient to allow the proximal portion of the introducer needle to extend therethrough but that is too small to allow the enlarged diameter portion of the introducer needle from passing therethrough.
The means for engaging the distally facing shoulder of the introducer needle can take many forms. For example, a spring gate can be located in a hollow cavity portion of the main body portion of the needle shield and about a portion of the introducer needle. The spring gate has a generally U shaped configuration with a pair of tines that allow the introducer needle to pass between the tines. A biasing mechanism forces the spring gate up into contact with the introducer needle. When the introducer needle is withdrawn proximally into the needle shield, the introducer needle rides past the tines. When the enlarged diameter portion passes by the tines, the spring gate is forced downwardly against the bias of the biasing mechanism to allow the enlarged diameter portion of the introducer needle to pass proximally past the spring gate. The proximal movement of the introducer needle into the needle shield is facilitated by a tapered portion of the introducer needle immediately proximal of the enlarged diameter portion that ensures a smooth transition from the proximal portion of the introducer needle to the enlarged diameter portion. Once the distally facing shoulder is proximal of the spring gate, the biasing mechanism forces the spring gate into engagement with the shaft of the introducer needle. This ensures that the introducer needle engages the spring gate so the tines extend up past the introducer needle. If a clinician then tried to advance the introducer needle distally, the distally facing shoulder would butt up against the spring gate which in turn would butt up against the distal wall of the cavity in the main body portion and prevent the introducer needle from being moved distally. Thus the sharp distal tip of the introducer needle would be prevented from being reexposed distally from the needle shield.
A variation of the spring gate discussed above is a leaf spring. The leaf spring has a proximal wall, a support leg and a locking leg. The support leg and the locking leg are configured into a generally V-shape, with the apex of the V facing distally. The locking leg is contoured to approximate a portion of the circumference of the introducer needle and rides along the introducer needle shaft. The configuration of the leaf spring ensures that the locking leg is biased toward the introducer needle but can be moved down away from the introducer needle so that the locking leg can ride over the enlarged diameter portion as the introducer needle is moved proximally into the needle shield. Once the distally facing shoulder is moved proximally of the proximal end of the locking leg of the leaf spring, the locking leg moves back into contact with the shaft of the introducer needle. If the introducer needle is moved distally, the proximal end of the locking leg of the leaf spring will engage the distally facing shoulder and prevent further distal movement of the introducer needle.
An alternative means for engaging the distally facing shoulder is a tube formed in the main body portion. The tube is coaxially located in the longitudinal passage of the main body portion and includes at least one movable lanced protrusion or tab that extends inwardly into the tube. Because the tab is movable, the distally facing shoulder can move proximally past the tab. Once the introducer needle has been withdrawn proximally into the needle shield such that the tab is distal of the distally facing shoulder, any distal movement of the introducer needle will be prevented when the distally facing shoulder engages the tab.
Yet another means for engaging the distally facing shoulder is a disk that is formed in or added to the main body portion. The disk is coaxially located in the longitudinal passage of the main body portion and defines a through hole and at least one proximally oriented, inwardly extending tab adjacent the through hole. The tab is also preferably oriented at an angle less than 90 degrees to the introducer needle. The through hole should be slightly larger than the diameter of the introducer needle to allow the major portion of the introducer needle to pass therethrough. Because the tab is movable, the distally facing shoulder can move proximally past the tab. Once the introducer needle has been withdrawn proximally into the needle shield such that the tab is distal of the distally facing shoulder, any distal movement of the introducer needle will be prevented when the distally facing shoulder engages the tab. In addition, since the tab is proximally oriented at an angle less than 90 degrees to the introducer needle, additional force would be required to allow the introducer needle to be subsequently moved distally. And in certain instances a distally facing shoulder may not be necessary as long as the tab engages the surface of the introducer needle if it is moved distally.
The distal portion of the needle shield includes a plurality of longitudinally extending fingers and radially inwardly extending projections that engage the proximal end of the catheter hub. This ensures that the needle shield remains engaged with the catheter until the introducer needle has been completely removed from the catheter and is safely shielded in the needle shield.